Process of producing paints and stains



Patented June 14, 1927.

UNETED STATES GEORGE WASHINGTON CARVER, 0F TUSKEGEE, ALABAMA.

PROCESS OF PRODUCING PAINTS AND STAINS.

No Drawing. Original application filed J'une'13, 1923, Serial No. 645,199. Divided and this application filed January 29, 1925. Serial No. 5,638. i

The invention relates to paints and stains, and has as an object the provision of a proce'ss for producing paints and stains from clays. Clays are found in many sections of the country of a variety of colors, and by a proper choice of color there may be pro duced by the process of the invention a large variety of colors of pigments, fillers and stains for treating wood or other materials.

To carry out the process of the invention the desired clay having "a high percentage of iron is treated by any of the well known processes for refining the same and reducing it to a finely divided condition. A desirable composition for a clay to be treated by the process of the present invention is 5.6% peroxide of iron and 16.7% aluminum.

While a clay testing as above described and substantially free from lime or any similar alkali is suitable for the carrying out of a process without the addition of free iron, yet a higher iron content will vary the effect only by improving the result.

To reduce the clay to a gelatinous condition the same is treated with acid. For this purpose taking as a basis a quantity of 25 pounds of clay free from sand or other objectionable substances, 25 pounds of commercial sulphuric acid and 25 pounds commercial hydrochloric acid may be added to the clay, with three pounds of clean scrap iron of any kind, iron turnings being a desirable form for the iron. The clay and iron are put into an acid-proof vessel which is.

capable of withstanding heat, as for instance a porcelain vessel. The acids are added with enough water to make a thin paste.

The substance is then boiled slowly, withuntil the iron is dissolved.

frequent stirring, and the whole mass assumes a uniform color.

Water free from alkali is then added sufficient to substantially double the volume, when the solution is well stirred and allowed to settle for about five minutes, for thepurpose of settlement of coarser portions. The material remaining in suspension with the liquid is then decanted into shallow acidproof vessels and the remaining coarse and insoluble material is thrown away.

The material thus secured is utilized as a base for subsequent steps, the nature of which, as well as the nature of the clay first taken for treatment may be chosen to vary the color of the resultant products.

As a next step, when it is desired to procyanide, 12 pounds of concentrated nitric acid is added to the thus prepared mixture and allowed to stand until a rich blue color appears. This is stirred at intervals of about two weeks for substantially three months, for the purpose of oxidizing the ma terial. At the end of this time the mass may be allowed to dry out until it is almost dry when it may bewashed thoroughly to remove excess acid if a neutral pigment is desired. If an acid pigment is wanted the mass may be dried without washing.

T he same result may be secured by a quick process,

except that it-is found that the resulting blue color is not so fine as that produced by the slow process above described. To quicken the process immediately after adding nitric acid live steam is turned into the mixture for bringing about the oxidation, and the mixture is constantly agitated with giving oft of brown fumes. After the fumes cease to be given off, the material may be treated as above described at the end of the two months period.

As a variation of the above process the nitric acid may be added with the sulphuric and hydrochloric, but it is found that slightly inferior results are thus obtained. Moreover copperas may be substituted for the scrap iron with, however, probably not such fine results.

For use as a wood filler or stain, clay of a desired color may be treated with the acid as above described, with omission of the potassium ,ferricyanide, and the thus secured gelatinous clay is found to strike into the wood fiber and to produce an exceedingly smooth surface, giving a color thereto dependent upon the color of clay chosen for treatment, thereby acting as a filler and stain withthe single application. It is found that a filler made as thus described becomes very hard when dry and enables the wood l blue filler and stain.

more beautiful than when first treated. For

this use the iron scrap may be omitted if desired, especially when; the potassium ferricyamde 1s not to be added to produce the To produce a green stain and filler, the clay treated as above described, withpotassium ferricyanide or potassium ferrocyanide, has added thereto a yellow ochre previously treated with acid as described in the beginning of the first portion of the process. To produce a mahogany brown, or red, the clay to be treated with the potassium ferricyanide has added thereto potassium sulphocyanide.

I When the resultant substance has been aplied to wood and allowed to oxidize a rich rown color results. By mixing the blue clay roduct with red, yellow, brown, pink, pump e, or white clay, a large variety of colors'and shades may be produced which may be used as fillers and stains. Any of these materials can be used either in the acid condition or neutralized by washing.

The material thus described as a compound filler and stain, may be dried and mixed with linseed oil or its equivalent as a igment 'to provide a paint. If desired to be darkened to a slight extent some good grade of carbon or lam black may be added. When the above aci treatment is carried out utilizing amicaceous clay of the variety of shades which occur in the southern States, a sheen results that has not to my knowledge been secured by heretofore used artificial mixtures.

This application is filed as a division of my former application for atent on Paints and stains and process 0 producing the same, ,Patent No. 1,51,478 granted June 9,

1925. a a Minor, changes may be made in the steps of the process and the f t e parts used without departing from roportion o P the spirit of my invention. I T I claim: f '1. The process of producing pigment or the like which comprises treating ferruginous clay with acid, and adding a'potassiumiron-cyanogen compound.

2. The process of producing pigmentor the like which comprises treating a ferrucease. 7 8. Boiling ginous'cla with sulphuric and hydrochloric acids, an adding a potassium-iron-cyanogen compound.

3. The

chloric acids, adding a solution of a potassium-iron-cyanogen compound, and treating themixture with nitric acid.

4. The recess of producing pigment or the like w ich com rises adding scrap iron to finel subdivide and refined clay, adding aci to the mixture and allowing action to continue until the iron is dissolved, adding a compound of potassium, iron and cyanogen and separating the coarser partlcles therefrom by decantation.

5. The process of producing pigment or the like w rich comprises treating a mixture of clay and free iron with acid, adding a solution of a potassium, iron, cyanogen compound, allowing the material to stand for an extended period of time with occasional stir-...

ring, and drying the product.

6. The recess of producing pigment or the like w ich comprises treatm a mixture of clay and free iron with aci adding a solution of a otassium, iron, cyanogen compound, allowmg the material to stand for an extended stirring, was ing the material free from acid, and drying the product,

7. Theprocess of producing pigment or the like which comprises adding substantial- 1y three pounds of scrap iron to substantially twenty-five pounds of clay substantially free from sand or alkali, adding a mixture of twenty-five pounds of sul huric and twenty-five pounds of hydrochloric acid with sufiicient water to make a thin paste, boiling the mixture, addin to the thus pre pared substance twentyve pounds of a potassium, iron, cyanogen compound dissolved in water, adding to the mixture twelve and one-half pounds of nitric acid and stirring the mixture until the fumes and addin the same to the material prepared by t e process of claim 2 to roduce'a color dependent upon the color 0 the prepared and added clay.

GEORGE WASHINGTON CARVER.

eriod of time'with occasionalclay of desired color with acid 

